[PATCH] asm-underscore: Fix mingw build

[Martin Kletzander]

Commit 54615b95ff238e235e806855efc46a9abad09f2e changed the regular
expression for detecting C symbol prefixes but forgot to qoute square
brackets in the command line arguments for grep.  That way when
building with mingw the condition was false although it ought to be
true instead.  In particular scenarios this led to the following
compile error:

    Cannot export rpl_printf: symbol not found
    Cannot export rpl_scanf: symbol not found
    collect2: error: ld returned 1 exit status

Fix this by properly quoting square brackets.

Signed-off-by: Martin Kletzander <address@hidden>
---
 m4/asm-underscore.m4 | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/m4/asm-underscore.m4 b/m4/asm-underscore.m4
index 547dd62d26a4..feca18db9bd6 100644
--- a/m4/asm-underscore.m4
+++ b/m4/asm-underscore.m4
@@ -29,7 +29,7 @@ int foo(void) { return 0; }
 EOF
      # Look for the assembly language name in the .s file.
      AC_TRY_COMMAND(${CC-cc} $CFLAGS $CPPFLAGS $gl_c_asm_opt conftest.c) 
>/dev/null 2>&1
-     if LC_ALL=C grep -E '(^|[^a-zA-Z0-9_])_foo([^a-zA-Z0-9_]|$)' 
conftest.$gl_asmext >/dev/null; then
+     if LC_ALL=C grep -E '(^|[[^a-zA-Z0-9_]])_foo([[^a-zA-Z0-9_]]|$)' 
conftest.$gl_asmext >/dev/null; then
        gl_cv_prog_as_underscore=yes
      else
        gl_cv_prog_as_underscore=no
-- 
2.9.0